The present invention relates to toothbrushes and, in particular, it concerns a toothbrush with longitudinal to lateral motion conversion.
It is known that best results are achieved by brushing teeth with an upwards and downwards action, thereby helping to remove food material stuck in the cracks between adjacent teeth. In practice, however, only a small proportion of users actually take the trouble to perform such a brushing action. Instead, most users revert to the much easier, but less effective, side-to-side brushing action.
In power-driven toothbrushes, this problem is commonly addressed by causing vibration or rotation of brush elements perpendicular to the handle (which is generally parallel to the side-to-side primary direction of motion). Examples of power-driven toothbrushes which employ such an action may be found in U.S. Pat. No. 2,583,886 to Schlegel, U.S. Pat. No. 2,665,675 to Grover, and U.S. Pat. No. 5,864,911 to Arnoux et al.
In the field of manual toothbrushes, however, the problem is not so readily solved. A wide variety of toothbrush structures have been proposed in an attempt to produce a secondary up-down motion even when the user only actively moves the toothbrush in a side-to-side primary direction of motion. Many of these employ rotatable bristle-carrying elements deployed so as to rotate about an axis perpendicular to the primary direction of motion. Examples of such structures may be found in U.S. Pat. No. 5,142,724 to Park, U.S. Pat. No. 5,186,627 to Amit et al., and U.S. Pat. No. 5,996,157 to Smith et al. None of these, however, has been found particularly effective.
An alternative solution is suggested in U.S. Pat. No. 1,643,217 to Lazarus. Here, a spiral arrangement of bristles extends along a rotatable shaft rotatably mounted parallel to the primary direction of motion. The description states that xe2x80x9cthe spiral arrangement of the bristle tufts tends to cause the bristle member, when rubbed against the teeth or the like, to rotate on the handle and so to bring a fresh surface continually into use.xe2x80x9d In practice, however, since the axis of rotation is parallel to the direction of motion, it is clear that little or no rotation would actually be induced.
There is therefore a need for a manual toothbrush which would effectively produce a secondary up-down motion when the user only actively moves the toothbrush in a side-to-side primary direction of motion. It would also be highly advantageous to provide a method for brushing along a row of teeth so as to generate a brushing action perpendicular to a direction of motion.
The present invention is a toothbrush with longitudinal to lateral motion conversion.
According to the teachings of the present invention there is provided, a toothbrush for brushing teeth within a mouth of a user, the toothbrush comprising: (a) a handle configured to define a primary direction of insertion of the toothbrush into the mouth; and (b) a plurality of rotatable brush assemblies mechanically linked so as to move together with the handle, the rotatable brush assemblies being deployed so as to define a plane of contact with the teeth, each of the rotatable brush assemblies including a wheel configured to be rotatable about an axis, the wheel having a plurality of bristles projecting substantially radially therefrom, wherein each of the rotatable brush assemblies is configured such that its aforementioned axis lies substantially parallel to the plane of contact and is inclined relative to the primary direction of insertion by an angle of between about 15xc2x0 and about 75xc2x0.
According to a further feature of the present invention, the axis of each of the rotatable brush assemblies is inclined relative to the primary direction of insertion by an angle of between about 30xc2x0 and about 60xc2x0, and more preferably, between about 40xc2x0 and about 50xc2x0.
According to a further feature of the present invention, the plurality of rotatable brush assemblies includes a first group for which the axis of rotation is inclined in a first sense relative to the primary direction of insertion and a second group for which the axis of rotation is inclined in a second sense, opposite to the first sense, relative to the primary direction of insertion.
According to a further feature of the present invention, the first group includes a plurality of the rotatable brush assemblies arrayed along a first line substantially parallel to the direction of insertion, and wherein the second group includes a plurality of the rotatable brush assemblies arrayed along a second line, parallel to but displaced from the first line.
According to a further feature of the present invention, each of the rotatable brush assemblies includes at least one feature configured to inhibit rotation of the wheel in a given direction about the axis.
According to a further feature of the present invention, each of the rotatable brush assemblies is mounted relative to the handle via a swivel mounting such that the rotatable brush assemblies can swivel about a swivel axis substantially perpendicular to the plane of contact, the swivel axis being offset relative to the axis of rotation of the wheel.
According to a further feature of the present invention, there is also provided a toothbrush head portion integrally formed with the handle, the head portion including a recessed socket for each of the rotatable brush assemblies, a part of each rotatable brush assembly being received within a corresponding one of the recessed sockets.
There is also provided according to the teachings of the present invention, a method for brushing along a row of teeth so as to generate a brushing action perpendicular to a direction of motion, the method comprising: (a) providing a toothbrush including at least one rotatable brush assembly including a wheel configured to be rotatable about an axis, the wheel having a plurality of bristles projecting substantially radially therefrom; (b) positioning the toothbrush with a number of the bristles in contact with a part of the row of teeth; and (c) moving the toothbrush along the row of teeth in a direction of motion, wherein the at least one rotatable brush assembly is oriented with its axis inclined at an angle of between about 15xc2x0 and about 75xc2x0 to the direction of motion such that rotation of the wheel caused by the movement generates a component of motion of the bristles substantially perpendicular to the direction of motion.
According to a further feature of the present invention, the at least one rotatable brush assembly is oriented with its axis inclined at an angle of between about 30xc2x0 and about 60xc2x0, and more preferably, between about 40xc2x0 and about 50xc2x0, to the direction of motion.